ON A KILLER’S TRAILWhile on a mission to bring his sister’s killer to justice, bounty hunter Riley Martelli spots a missing FBI agent in a Colorado national park. When he calls in the tip, he’s joined in his search by Special Agent Harper Prentiss. Harper, aided by her faithful German Shepard, is determined to locate the missing agent…without falling for the charms of the handsome bounty hunter. Working together is the best option to find their targets, but it also doubles the danger they're in. With a killer looming large, poised to end their search for good, can Riley and Harper unite to find both men without becoming the next victims?Classified K-9 Unit: These lawmen solve the toughest cases with the help of their brave canine partners.